Yet it would be tough for her to be any safer, politically, as she looks toward re-election in 2014.

“She may be the strongest Republican incumbent in the country,” GOP consultant Erik Potholm, who hails from Maine, wrote in an email. “She has sky high approval numbers and has become a political rock star in Maine.”

“In the past she has easily crushed top tier Dem challengers like [former Rep.] Tom Allen and [now-Rep.] Chellie Pingree,” he added. “I doubt any credible Dems will take her on this cycle. They would be crazy to do so.”

“I think she’s fine,” said Maine political consultant Dennis Bailey, who is a registered Democrat. “I don’t see any vulnerability.”

But in 2008, despite a wave election for Democrats and a strong challenge from Allen, Collins won by 22 points. She won her first re-election in 2002 with a comfortable 58 percent of the vote against Pingree.

Safe from a real Democratic challenge, Collins’ vulnerability from the right also appears marginal.

One name floated as a potential Republican challenger is former state Treasurer Bruce Poliquin, who came up short in the GOP primary for Senate in 2012.

Tyler Harber, a GOP consultant who is close to Poliquin, said that the former state treasurer has been approached to run against Collins or for one of Maine’s two House seats but Poliquin “hasn’t made a decision yet as far as I know.”

“He’s so deliberate, it will probably be awhile before he makes a decision,” Harber said. “I’d be surprised if he jumped in against Susan Collins, but anything is possible.”

A Collins spokesman said she remained focused on her job and “not on the campaign.”

There remains, of course, the possibility of any number of conservatives trying to challenge Collins from the right in a GOP primary. But Pine Tree State insiders don’t see any genuine threats on the horizon, despite her moderate voting record. In 2011, in votes where a majority of Democrats opposed a majority of Republicans, Collins voted with her party only 48 percent of the time.

Longtime Maine conservative activist Mary Adams, who ran against Collins in the 1994 Maine GOP gubernatorial primary, said the senator was in good shape.

“I probably don’t agree with her on 50 percent of her votes, and I can’t get her to sign the Taxpayer Protection Pledge,” Adams said with frustration. But, she added, when Republican primary day rolls around next year, the senator will have her vote.